Silver nanoparticles as antimicrobial agent: a case study on E. coli as a model for Gram-negative bacteria

• Published in: Journal of colloid and interface science 2004-07, Vol.275 (1), p.177-182
• Main Authors: Sondi, Ivan, Salopek-Sondi, Branka
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Bacteria; Bactericide; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Cell Proliferation - drug effects; Cell Wall - metabolism; Cell Wall - ultrastructure; Chemistry; Colloidal state and disperse state; E. coli; Escherichia coli - growth & development; Escherichia coli - ultrastructure; Exact sciences and technology; General and physical chemistry; Nanoparticles; Nanostructures; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Silver; Silver - pharmacology
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2004.02.012

The antimicrobial activity of silver nanoparticles against E. coli was investigated as a model for Gram-negative bacteria. Bacteriological tests were performed in Luria–Bertani (LB) medium on solid agar plates and in liquid systems supplemented with different concentrations of nanosized silver particles. These particles were shown to be an effective bactericide. Scanning and transmission electron microscopy (SEM and TEM) were used to study the biocidal action of this nanoscale material. The results confirmed that the treated E. coli cells were damaged, showing formation of “pits” in the cell wall of the bacteria, while the silver nanoparticles were found to accumulate in the bacterial membrane. A membrane with such a morphology exhibits a significant increase in permeability, resulting in death of the cell. These nontoxic nanomaterials, which can be prepared in a simple and cost-effective manner, may be suitable for the formulation of new types of bactericidal materials.